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Wildlife officials next week will begin returning fish to the urban lake struck by a devastating die-off last December.

About 8,000 rainbow trout will be stocked in Sparks Marina Tuesday after a third round of tests showed dissolved oxygen levels throughout the lake are sufficient to safely support fish again.

"The levels have held and they are at sufficient levels we're confident we can stock the fish and there won't be any problem," said Chris Healy, spokesman for the Nevada Department of Wildlife.

An estimated 100,000 trout, catfish and bass died in mid-December in an event experts believed was linked to near-zero temperatures that hit the Reno-Sparks area during a winter cold snap. Those bone-chilling temperatures likely caused oxygen-rich waters on the surface to quickly cool and sink to the bottom in what is known as a "violent turnover." Algae growth in the 77-acre lake during a hot summer may have helped further diminish oxygen levels.

Tests conducted by the city of Sparks in late February showed oxygen levels were returning to normal. Two additional tests in March, the last conducted Thursday, indicated oxygen levels were maintained across the lake and at depths of up to 50 feet.

That means the Department of Wildlife can now begin the process of restoring the fishery at the one-time gravel pit that is now a popular recreational destination.

"It's good news because it's always been a popular fishery," Healy said.

As many as 26,000 trout, possibly more, will be stocked there this year. It's unknown when warm water fish — bass and catfish — might be stocked there again.

Fully restoring the fishery will take time, Healy said.

"People will be able to catch fish but you have a whole big lake there without any fish in it so it's going to take a while to get the fishery back like it was," Healy said.

Restocking plans mean the annual free fishing day, typically attended by thousands of youths, can proceed as planned June 14.